Objectives: 1. To characterize the internal phenotypes of various human aneuploid conditions (trisomies, partial trisomies, deletions). 2. To generate hypothesis which elucidate the development of abnormalities and variations in human aneuploids. 3. To generate data on the morphogenetic outcomes of particular excess (trisomies) or deleted (partial monosomies) chromosomal material. 4. To make a distinction between the effects of specific chromosomal material (e.g. deletions) as contrasted with the non-specific DNA dose effect. 5. To elucidate the sequence of events in normal morphogenesis and the obligatory system interactions during development. Methods: 1. Bodies of children and fetuses with cytogenetically confirmed aneuploid conditions will be obtained from Children's Hospital, National Medical Center, Washington D.C., and the Anatomy Department, University of Wisconsin-Madison. Multiple congenital anomaly syndromes, other than chromosomal e.g. cebocephaly, Hanhart's will also be accepted. 2. The specimens will be dissected in a complete fashion and the data will be compiled, organized, compared and analyzed.